xen proposal

[Kostas Georgiou]

On Fri, Apr 18, 2008 at 04:39:18PM -0500, Mike McGrath wrote:

> On Fri, 18 Apr 2008, Kostas Georgiou wrote:
> 
> > On Fri, Apr 18, 2008 at 03:33:22PM -0500, Mike McGrath wrote:
> >
> > > The only reason we haven't done this already is the inability to detect if
> > > the box is already up somewhere (which is something we need already)
> > > Consider this scenario:
> > >
> > > app1 running on xen1 (which is having high load from koji1 also on xen1)
> > >
> > > People complain about the wiki.
> > >
> > > We move app1 to a more free box, xen7.
> > >
> > > high load causes CRASH
> > >
> > > xen1 reboots.  Attempts to bring app1 up (already up on xen7)
> > >
> > > Two machines try to write to the same disk - DOOM.
> >
> > What about using gfs (or maybe just nfs from the netapp) to keep the
> > contents of /etc/xen/auto "synced" between hosts? Having /etc/xen/auto
> > as a link to [sharedarea]/auto-xenXX and making sure that the entries
> > there are unique will be a good start for a solution I think.
> >
> 
> Network file shares are ill suited for tasks like configuration management
> IMHO.

I don't disagree, I don't like it either.
RedHat magazine had an article[1] recently about xen failover using
conga. It might give some ideas even if you prefer not to use gfs
(probably a bad idea to have host images in gfs anyway).

Kostas

[1] http://www.redhatmagazine.com/2007/08/23/automated-failover-and-recovery-of-virtualized-guests-in-advanced-platform